Determination of Chloramphenicol in Honey, Shrimp, and Poultry Meat with Liquid Chromatography–Mass Spectrometry: Validation of the Method According to Commission Decision 2002/657/EC

Chloramphenicol (CAP) is an antibiotic used for the treatment of bacterial infections in human and veterinary medicine. The use of CAP was prohibited in the European Union in 1994. Control laboratories are required to use suitably validated analytical methods to check sample compliance with the regulation. A quantitative method based on liquid chromatography coupled to isotopic dilution tandem mass spectrometry was developed for the determination of chloramphenicol in honey, shrimp, and poultry meat. The experimental protocol consisted of a liquid–liquid extraction with ethyl acetate. Separation and detection were realized, respectively, by a 2690 Waters HPLC (Milford, MA, USA) and a Micromass Triple Quadrupole mass spectrometer (Micromass, Manchester, UK), equipped with an electrospray source. The effects of mobile-phase additives on the response of LC/ESI/MS were examined. Two different HPLC columns were tested: the X-Terra from Waters and the Alltima HP C18 HL from Alltech (Deerfield, IL, USA). A validation of the method was conducted according to the EU criteria for the analysis of chloramphenicol in foods. The decision limits (CCα) were 0.04, 0.03, 0.07 μg?kg^?1, and the detection capabilities (CCβ) were 0.05, 0.04, 0.08 μg?kg^?1 for honey, shrimp, and poultry meat, respectively. Those values are below the minimum required performance limit set at 0.3 μg?kg^?1 by the EU and 0.1 μg?kg^?1 by Belgium. Our protocol has the advantage to propose a unique extraction method working as well for honey, shrimp, and poultry meat, contrary to similar published methods in which a different extraction method is used for each type of matrix.     

Assessing dioxin precursors in pesticide formulations and environmental samples as a source of octachlorodibenzo-p-dioxin in soil and sediment

An as yet unidentified origin of elevated concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) in soil and sediment has repeatedly been described from different locations around the world, including Australia. Natural sources have been hypothesized to account for such contamination, which is characterized by a distinctive dioxin profile, in particular, elevated levels of octachlorodibenzo-p-dioxins (OCDD) as well as relatively low contributions of polychlorinated dibenzofurans (PCDFs). The present study investigated whether OCDD formation via anthropogenically derived precursors represents a possible source in such samples. Soil and sediment from Australia and Hawaii were screened for known pesticide derived dioxin precursors. Two pesticide formulations containing pentachlorophenol (PCP), which are well-known to contain predominantly OCDD impurities, were also analyzed. Polychlorinated phenoxyphenols (PCPPs), common byproducts of pesticide production, were detected at parts-per-billion (ppb) levels in two PCP formulations and in five environmental samples. Of particular interestwasthe presence of the PCPP isomer 3,4,5,6-tetrachloro-2-(2,3,4,5,6-pentachlorophenoxy)phenol (nonaC2PP), often also termed predioxin, in these samples. This compound readily undergoes ring closure to form OCDD under a range of conditions and environments. In addition, the pesticide PCP itself, which also represents a potent precursor to OCDD formation and is known to contain OCDD impurities, was detected in some environmental samples. The evidence from this study indicates that pesticides and their impurities play an important role in the dioxin contamination of Australian soils and sediments, as well as other locations with similar PCDD/F patterns. The results further suggest that formation of OCDD from pesticide derived precursors may be a possible past, present, and future pathway for contamination of environmental samples.     

Digestion stability and evaluation of the metabolism and transport of olive oil phenols in the human small-intestinal epithelial Caco-2/TC7 cell line

The aims of this study were to investigate (i) the metabolism of olive oil phenolics by intestinal epithelial cells and (ii) their transport across epithelial cell monolayers. The various conjugates and derivatives produced by the intestinal epithelial cells were identified following separation by ultra-performance liquid chromatography (UPLC), using a combination of UV/visible spectra, mass spectrometry and specific enzyme treatments (β-glucuronidase and aryl-suphatase). Limited metabolism of olive oil phenolics was observed using Caco-2/Tc7 cells as a model of the human intestinal epithelium, and the methyslated conjugates were the major metabolites detected. The results of the transport rate data for phenols and their metabolites to the apical, cellular, and basolateral compartments after apical loading of the phenol at 100 μM showed a time-dependent efflux of various free and conjugated forms of phenols.     

Influence of chemical and physical modification on the bile acid binding capacity of dietary fibre from lupins (Lupinus angustifolius L.)

Bile acid adsorption by dietary fibre in the human intestine is widely considered to be a mechanism for lowering the blood cholesterol level and reducing the risk of colon cancer. In this study, the influence of physical and chemical treatment on the bile acid binding capacity of lupin dietary fibres was determined in vitro. Various methods for modifying dietary fibres were investigated (enzymatic, acid, and alkaline hydrolysis, as well as acetylation). The bile acid binding capacity was measured using an enhanced in vitro digestion model. The native lupin fibre product showed a bile acid binding capacity of 19%, whilst the medication cholestyramine exhibited a binding capacity of almost 100%. Enzymatic and acid hydrolysis caused a significantly increased binding capacity of up to 38%, corroborating the importance of dietary fibre structure, composition, and degree of degradation as determining factors for the bile acid binding capacity. The results of the acetylation experiments support the hypothesis of a hydrophobic linkage between bile acids and dietary fibre. Furthermore, the binding capacity depends on the particle size distribution, and consequently on the particle specific surface area.     

Antioxidant activity of yoghurt peptides: Part 2 – Characterisation of peptide fractions

The aim of the present study was to elucidate previous findings showing that peptide fractions isolated from yoghurt had antioxidant effects. Therefore, peptides and free amino acids released during fermentation of milk were characterised. Yoghurt samples were stripped from sugars and lactic acid and subsequently fractionated by ultra filtration using membranes with cut off sizes of 30, 10 and 3 kDa. The peptides in these fractions were identified by LC–MS/MS. The identified peptides comprised a few N-terminal fragments of αs₁-, αs₂-, and κ-casein, and several fragments from β-casein. Almost all the peptides identified contained at least one proline residue. Some of the identified peptides included the hydrophobic amino acid residues Val or Leu at the N-terminus and Pro, His or Tyr in the amino acid sequence, which is characteristic of antioxidant peptides. In addition, the yoghurt contained a considerable amount of free amino acids such as His, Tyr, Thr and Lys, which have been reported to have antioxidant properties. Thus, our findings confirm that the antioxidant effects of the peptide fractions from yoghurt are due to the presence of certain peptides and free amino acids with recognised antioxidant activity in these fractions.     

Prevalence of Mycobacterium avium ssp. paratuberculosis infections in Canadian dairy herds

Johne's disease is a progressive, chronic disease with inflammation of the small intestine of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). Accurately estimating prevalence of MAP infections is important when controlling spread of infection or monitoring effectiveness of control programs. In the absence of a consistent test method used in prevalence studies across Canada, prevalence estimates among regions and programs cannot be compared. The aim of the current study was to estimate and compare prevalence of MAP infection in Western Canada, Ontario, Québec, and the Atlantic provinces, as well as among varying herd sizes and housing types. On 362 dairy farms located in all 10 provinces of Canada, environmental samples were collected and cultured for detection of MAP. For each herd, 1 sample was collected from the lactating cow area and manure storage. An additional environmental sample was collected from the area where breeding-age heifers were housed. Using prior distributions from previous research, diagnostic sensitivity and specificity were calculated to assess the ability of only 2 environmental samples (manure storage and lactating cow area) to identify MAP-positive farms, resulting in a sensitivity and specificity of 38 and 100%, respectively. We found no difference in sensitivity and specificity when including breeding-age heifers environmental samples. Test characteristics were applied to environmental culture results from the 362 participating farms in all 4 regions, resulting in true prevalence estimates of 66% for farms in Western Canada, 54% in Ontario, 24% in Québec, and 47% in Atlantic Canada. Herds housed in tiestalls had lower prevalence than freestall-housed herds, and herds with 101–150 and >151 cows had higher prevalence than herds with ≤100 cows. This was the first time MAP prevalence was determined using 1 detection method, performed in 1 laboratory, and within a single year across Canada, enabling direct comparisons of prevalence among regions, housing types, and herd sizes.     

Migration of photoinitiators from cardboard into dry food: evaluation of Tenax® as a food simulant

Photoinitiators are widely used to cure ink on packaging materials used in food applications such as cardboards for the packaging of dry foods. Conventional migration testing for long-term storage at ambient temperature with Tenax^® was applied to paperboard for the following photoinitiators: benzophenone (BP), 4,4?-bis(diethylamino)benzophenone (DEAB), 2-chloro-9H-thioxanthen-9-one (CTX), 1-chloro-4-propoxy-9H-thioxanthen-9-one (CPTX), 4-(dimethylamino)benzophenone (DMBP), 2-ethylanthraquinone (EA), 2-ethylhexyl-4-dimethylaminobenzoate (EDB), ethyl-4-dimethylaminobenzoate (EDMAB), 4-hydroxybenzophenone (4-HBP), 2-hydroxy-4-methoxybenzophenone (HMBP), 2-hydroxy-4?-(2-hydroxyethoxy)-2-methylpropiophenone (HMMP), 2-isopropyl-9H-thioxanthen-9-one (ITX), 4-methylbenzophenone (MBP) and Michler’s ketone (MK). Test conditions (10 days at 60°C) were according to Regulation (EU) No. 10/2011 and showed different migration patterns for the different photoinitiators. The results were compared with the migration in cereals after a storage of 6 months at room temperature. The simulation with Tenax at 60°C overestimated actual migration in cereals up to a maximum of 92%. In addition, the effect of a lower contact temperature and the impact of the Tenax pore size were investigated. Analogous simulation performed with rice instead of Tenax resulted in insufficiently low migration rates, showing Tenax is a much stronger adsorbent than rice and cereals.     

Essential oils of four Rwandese hepatoprotective herbs: Gas chromatography–mass spectrometry analysis and antioxidant activities

Following an ethnobotanical survey in Southern Rwanda for hepatoprotective remedies, four food and medicinal plants, Crassocephalum vitellinum, Guizotia scabra, Microglossa pyrifolia and Ocimum lamiifolium, were selected for pharmacological and chemical investigations aiming to validate their reported properties. The chemical compositions of essential oils obtained from leaves were investigated by GC–MS; essential oils and methanolic extracts were evaluated for antioxidant activity by 1,1-diphenyl-2-picryhydrazyl (DPPH) and linoleic acid peroxidation assays. C. vitellinum [limonene (34.8%), (E)-β-ocimene (21.8%), β-pinene (8.5%), α-pinene (6.6%), myrcene (6.3%)], G. scabra [germacrene-d (25.5%), limonene (9.7%), (E)-β-ocimene (6.6%)], M. pyrifolia [germacrene-d (58.3%)] and O. lamiifolium [sabinene (12.2%), alpha phellandrene (11.6%)] volatile oils scavenge DPPH (10%, 39%, 27%, and 11% quercetin equivalents) and inhibit linoleic acid peroxidation (13%, 23%, 20%, and 13% Trolox® equivalents). The four methanolic extracts were quite active on the lipid peroxidation model (93%, 93%, 70%, and 67% Trolox equivalents) with modest activity on DPPH (5%, 10%, 8%, and 11% quercetin equivalents). These properties most probably participate in the four plants hepatoprotective activities reported in ethnopharmacological and/or pharmacological studies.